Various non-limiting embodiments disclosed herein relate to methods of making alignment facilities for optical dyes connected to at least a portion of an optical substrate. Other non-limiting embodiments related to optical elements, such as but not limited to ophthalmic elements, comprising an alignment facility for an optical dye. Still other non-limiting embodiments relate to alignment facilities for optical dyes comprising coatings or sheets of an at least partially ordered liquid crystal material.
Liquid crystal molecules, because of their structure, are capable of being ordered or aligned so as to take on a general direction. As used herein with reference to the order or alignment of a material or structure, the term “general direction” refers to the predominant arrangement or orientation of the material or structure. More specifically, because liquid crystal molecules have rod- or disc-like structures, a rigid long axis, and strong dipoles, liquid crystal molecules can be ordered or aligned by interaction with an external force or another structure such that the long axis of each of the molecules takes on an orientation that is generally parallel to a common axis. For example, if an electric or magnetic field is applied to a cell containing a disordered, fluid-mixture of liquid crystal molecules, the long axis of essentially all of the liquid crystal molecules can be ordered in a direction relative to the applied field. Once the field is removed, however, the molecules will again randomly distribute themselves in fluid-mixture.
It is also possible to align liquid crystal molecules with an oriented surface. That is, liquid crystal molecules can be applied to a surface that has been oriented, for example by rubbing, grooving, or photo-alignment methods, and subsequently aligned such that the long axis of each of the liquid crystal molecules takes on an orientation that is generally parallel to the general direction of orientation of the surface.
Aligning a liquid crystal material with an oriented surface as discussed above generally involves holding the liquid crystal material on the oriented surface at a temperature above the melting point of the liquid crystal material for some period of time to allow the liquid crystal molecules to align themselves. Although the time required for alignment depends on several factors, generally speaking, the thicker the layer of the liquid crystal material applied to the oriented surface, the longer the time required to fully align the liquid crystal material. Further, for some thick layers of liquid crystal materials, full alignment may not be achieved.
Photochromic compounds, dichroic compounds, and photochromic-dichroic compounds may be incorporated into a coating, a substrate or an organic material, for example a polymer coating. When photochromic compounds, dichroic compounds, and photochromic-dichroic compounds undergo a change from one state to another, the molecules of the photochromic compound, dichroic compound, or photochromic-dichroic compound may undergo a conformational change from a first conformational state to a second conformational state. In addition to a change in color and/or polarizing capability of the compounds, this conformational change may result in a change in the amount of space that the compound occupies. However, for certain photochromic compounds, dichroic compounds, or compounds photochromic-dichroic materials to effectively align and/or transition from one state to another, for example to transition from a clear state to a colored state, to transition from a colored state to a clear state, to transition from a non-polarized state to a polarized state, and/or to transition from a polarized state to a non-polarized state, the photochromic compound, dichroic compound, or photochromic-dichroic compound must be in an chemical environment that is sufficiently flexible to allow the compound to transition from a first conformational state to the second conformational state at a rate that is sufficient to provide the desired response over an acceptable time frame. Therefore, new polymeric materials are necessary to further develop photochromic, dichroic, and photochromic-dichroic materials and articles.